From the College of Medicine, Medical University of South Carolina, Charleston, South Carolina.

Supplemental Digital Content is available for this article (see supplemental digital figures 1 and 2, http://links.lww.com/ALN/B847). Direct URL citations are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).

Supplemental Digital Content is available for this article (see supplemental digital figures 1 and 2, http://links.lww.com/ALN/B847). Direct URL citations are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).×

Submitted for publication July 27, 2018. Accepted for publication November 20, 2018.

Submitted for publication July 27, 2018. Accepted for publication November 20, 2018.×

Address correspondence to Dr. Reves: College of Medicine, Medical University of South Carolina, Charleston, South Carolina 29403. revesj@musc.edu. Information on purchasing reprints may be found at www.anesthesiology.org or on the masthead page at the beginning of this issue. Anesthesiology’s articles are made freely accessible to all readers, for personal use only, 6 months from the cover date of the issue.

In this study, we examined the relationship of regional cerebral blood flow (CBF) to mean arterial pressure, systemic blood flow, partial pressure of arterial carbon dioxide (PaCO2), nasopharyngeal temperature, and hemoglobin during hypothermic nonpulsatile cardiopulmonary bypass (CPB). Regional CBF was determined by clearance of xenon 133 in 67 patients undergoing coronary bypass grafting procedures. There was a significant decrease in regional CBF (55% decrease) during CPB, with nasopharyngeal temperature and PaCO2 being the only two significant factors (p < 0.05). In a subgroup of 10 patients, variation of pump flow between 1.0 and 2.0 L/min/m2 did not significantly affect regional CBF. We conclude that cerebral autoregulation is retained during hypothermic CPB. Under the usual conditions of CPB, variations in flow and pressure are not associated with important physiologic or detrimental clinical effects.